Method of preventing &#34;killing&#34; of adhesive in the forming of bonding seams between sheet portions



' Oct. 5, 1943. J. L. SHIVELY 2,331,054

METHOD OF PREVENTING "KILLING" OF ADHESIVE IN THE FORMING OF BONDING SE MS BETWEEN SHEET PORTIONS Filed June 26, 1942 ATTORNEYS JAMES L. SH/VELY d INVENTOR $4 M fiw 11g 3 I BY Patented Oct. 5, 1943 METHOD OF PREVENTING KILLING OF ADHESIVE'IN THE FORMING OF BONDING SEAMS BETWEEN SHEET PORTIONS James L. Shively, Camas, wash assignor to Crown Zcllerbach (lorporatlon, San Francisco Calif., a corporation of Nevada Application June 26, 1942, Serial No. 448,677

3 Claims.

This application is a continuation in part and completion of my application for patent filed June 24, 1940, Serial No. 342,097.

My invention relates particularly to the making of the seams in the body of paper bags intended for containing finely powdered material, and which seams must therefore be siftprooi.

As well known, the body of this type of bag is commonly made in tubular form of a single sheet of paper, and the seam of the tube is formed by overlapping the longitudinal edges-portions of the I sheet and applying a narrow strip of paste or other adhesive to one of such portions, and then pressing these edge portions firmly together by passing the bag tube between draw-rolls.

I observed that in this operation the pressure applied by the draw-rolls upon the strip of paste interposed between sheet-portions tends "to kill the paste scam, as it were, more or less; in other words, tends to reduce this bonding seam of adhesive to so thin a film as to be unreliable as an adhesive medium; and in consequence the pressure of the material in th bag will cause the sheet-portions frequently to come apart at the seam rendering the bag no longer siftproof.

The object of my invention i to improve the process of making the paste seam of the bag tube so as to prevent the reducing of the film 9f adhesive between the two sheet-portions to a lifeless film in the step of obtaining bonding contact between the overlapped seam'portions by passing between the draw rolls. To this end my invention consists of the improved method of forming a bonding seam between two sheet portions of material, said method comprising arranging the two sheet portions so that their longitudinal'edges overlap; applying a layer of adhesive between the opposed faces of said overlapping edges, and then passing said overlapping edges and interposed layer of adhesive between pressing devices. for example .draw rolls, the pressing surface of one of he devices having been provided with continuous grooves arranged substantially in reticulate formation of sufficient width and depth so that the said pressing will cause part of said layer of adhesive to be squeezed into and collected in conthe lines should 'all run diagonally with respect to the edge of the seam.

The manner of carrying my invention into practice is illustrated in the accompanying drawh igure l is a perspective view illustrating the 7 practice of my method and as apparent shows two draw rolls superimposed one on the other as usual, the bearings of the draw rolls not being shown, and the pasted seam of two overlapping sheetportions being passed between the draw-rolls to complete the bonding seam by pressing the sheetportions firmly together, the lower of the draw rolls having the usual smooth peripheral urface, but the upper draw roll being grooved asmentioned;

Figure 2 shows a fragmentary section .of a pcripheral portion of the grooved draw roll;

Figure 3 illustrates on enlarged scale, diagram matically, the operation of my invention; and

Figure 4 illustrates, diagrammatically, the dishas cut into it reticulate grooves vc extending completely across the draw roll, all of which grooves extend diagonally with respect to the axis of the draw roll and preferably are arranged so tinuous retlculate lines corresponding to said.

"as to intersect each other at angles of less than- The grooves 0 should be of suricient width and depth to cause the adhesive between the sheet portions tobe pressed into substantial continuous lines. I have found it satisfactory to' make the grooves of from 54; inch to la inch wide and approximately inch deep. I have also found itsatisfactory to space the groovesfrom of an inch to-one inch apart.

The pressure exerted between draw rolls a and b upon the overlapping sheet portions e,. f and the layer of paste or adhesive between them causes the progressive squeezing of the entire area of the adhesive into continuous reticulate lines and the sheet portion directly overlying the 1 grooves c to'be distended into continuous chan-' nels receiving and holding the said lines of adhesive. The retention of'these retlculate of adhesive in said channels prevents the "kill? ing" of said lines of adhesive during the pressinfi of the sheet portions together between draw mus:

Referring-to Figures 1 and 3 it is assumed that a layer of adhesive is applied either to the opposed face of the'upper sheet portion e or to the opposed face of the lower sheet portion 1, such adhesive being applied by any convenient oustomary paste-applying means. and it is assumed that the two sheet portions have been introduced between the two draw rolls. In passing between the draw rolls a and b the sheets e, f are firmly pressed together as represented in Figs. 1 and 3, the layer of adhesive being indicated at y in Fi 3.

The intersection and continuity of the grooves e and the fact that they extend diagonally across the seam area and that they have open ends provide for the lineal movement of the surplus paste in the channels without interfering with the pressing of the sheet portions firmly together while these are passing through the draw rolls.

The pressure exerted by the surface areas at of the grooved draw roll b causes the two draw rolls to coact in obtaining a firm grip upon the bonded sheet portions of paper and thus afiect their progressive advancement through the draw rolls. i

Whenv the bonded sheet portions constituting the seam have left the draw rolls the upper sheet portion, assuming that the grooved roller b is the top roller, will show the distention markings as indicated in Figure 1 and diagrammatically illustrated on more or less exaggerated scale in Figure 4. The pattern of the distention markings will show the reticulate channels formed in the upper sheet portion within which the lines of adhesive have been retained.

I claim:

,1. The improved method of forming a bonding seam between two sheet portions of material, said method comprising arranging the two sheet portions so that their longitudinal edges overlap, applying a layer of adhesive between the opposed faces of said overlapping edges, passing said overlapping edges and interposed layer of adhesive between pressing devices, forming open ended, reticulated ridges extending across the seam in one of the sheet portions, and squeezing the adhesive into the ridges from the areas between the ridges, thereby collecting the adhesive in the idges in thicker portions than in the areas between the rldges, and thereby preventing the killing of the adhesive and assuring the bonding of the sheet portions completely across said seam.

2. The improved method of forming a bonding seam between two sheet portions of material, said method comprising arranging the two sheet portions so that their longitudinal edges overlap; applying a layer of adhesive between the opposed faces of said overlapping edges, forming open ended ridges in one of the sheet portions extending across the seam obliquely and substantially in reticulate formation, said ridges each being about inch wide and inch deep, and squeezing the adhesive into the ridges from the areas between the ridges, thereby collecting the adhesive in the ridges in thicker portions than in the areas between the ridges, and thereby preventing the killing of the adhesive and assuring the bonding of the sheet portions completely across said seam.

3. The improved method of forming a bonding seam between two sheet portions of material, said method comprising arranging the two sheet portions so that their longitudinal edges overlap, applying a layer of paste between the opposed faces of said overlapping edges, passing said overlapping edges and the interposed layer of paste between pressing devices, forming open ended ridges extending across the seam in one of the sheet portions in reticulate formation, said ridges being about inch wide and 1 inch deep and so arranged as to intersect each other at less than and squeezing the paste into the ridges from the areas between the ridges, thereby collecting the paste in the ridges in thicker portions than in the areas between the ridges, and thereby preventing the killing of the paste and as suring the bonding of the sheet portions completelyacross said seam.

JAMES L. SHIVELY. 

